Bearing devices with integrated electrical insulation, particularly for electric motors or machines, and associated manufacturing processes

Abstract

[Bearing device with integrated electrical insulation, particularly for electric motors or machines, and associated manufacturing processes] The bearing device comprises a bearing 10 having a first ring 12 and a second ring 14 capable of rotating relative to each other. The device includes at least one insulating sleeve 22 mounted on the second ring 14 of the bearing and having a bushing 28 and an insulating lining 30 overmolded at least on one of the outer and inner surfaces of the second ring 14 and at least on one of the outer and inner surfaces of the bushing 28 that define its radial thickness. The device further comprises at least one elastically deformable member 32 located radially between the second ring 14 and the bushing 28, and which is radially in contact with at least one of said surface of the second ring and of said surface of the bushing 28 when compressed in the radial direction. Reference: Figure 1

Description

Title of the invention: Electrically insulated bearing device, particularly for electric motors or machines, and associated manufacturing processes. Technical field of the invention

[0001] The present invention relates to the field of bearings used in particular in electric motors, electrical machines and associated equipment. Prior art

[0002] In an electric motor or machine, at least one roller bearing is mounted between the housing of the motor or electric machine and the rotating shaft in order to support this shaft.

[0003] During operation when the shaft is rotating, an electrical potential difference may appear between it and the housing of the motor or electrical machine, which generates an electric current between the inner ring of the bearing which is attached to the shaft, and the outer ring attached to the housing.

[0004] The electric current passing through the components of the rolling bearing can damage these components, in particular the rolling elements and the raceways formed on the inner and outer rings. Electrical discharges can also generate vibrations.

[0005] To overcome these drawbacks, it is known to replace the bearing's rolling elements, made of the same steel as the inner and outer rings, with rolling elements made of ceramic. This is generally referred to as a hybrid bearing.

[0006] However, such a hybrid bearing is relatively expensive.

[0007] To remedy the aforementioned disadvantages, it is also known to equip the outer ring of the bearing with an insulating sleeve provided with a bushing and an insulating lining made of electrically insulating material and interposed radially between the outer ring and the bushing.

[0008] In order to achieve the fixing of the insulation lining on the outer ring and on the sleeve without additional element or special machining on the outer ring, it is possible to overmold the insulation lining.

[0009] However, with such a solution, a relative separation of the insulation lining and the socket may occur during operation.

[0010] The present invention therefore aims to remedy the aforementioned drawbacks by proposing a bearing device of simple and economical design. Summary of the invention

[0011] The invention relates to a bearing device comprising a bearing provided with a first ring and a second ring capable of rotating relative to each other.

[0012] The device further comprises at least one insulating sleeve mounted on the second bearing ring. The insulating sleeve is provided with a bushing and an insulating gasket interposed radially between the second bearing ring and the bushing. The insulating gasket is made of electrically insulating material.

[0013] The sleeve comprises an outer surface and an inner surface opposite to the outer surface and which delimit the radial thickness of said sleeve.

[0014] The second ring comprises an outer surface and an inner surface opposite to the outer surface and which delimit the radial thickness of said second ring.

[0015] The insulation lining is overmolded at least on one of the outer and inner surfaces of the second bearing ring, and at least on one of the outer and inner surfaces of the bushing.

[0016] According to a general characteristic, the device further comprises at least one elastically deformable member which is located radially between the second ring and the sleeve and which is partially covered by the insulating lining.

[0017] By "elastically deformable organ", we mean a component capable, by virtue of the material used and / or its dimensioning, of deforming under the action of an external stress, and of tending to return by elasticity to its initial shape in the event of cessation of the stress.

[0018] By "organ located radially between the second ring and the bushing", we mean an organ which is located between the second ring and the bushing considering the radial direction, regardless of the presence or absence of another element radially between the organ and the second ring or radially between the organ and the bushing, for example the insulation lining.

[0019] According to another general characteristic, said elastic member is radially in contact at least with one of said surface of the second ring and said surface of the sleeve by being compressed in the radial direction.

[0020] Thus, an economical integrated electrically insulated bearing device is available compared to conventional hybrid rolling bearings. Furthermore, the device is easy to manufacture and assemble in the associated motor or electrical machine.

[0021] Furthermore, the provision of said elastically deformable element makes it possible to obtain good bonding in the circumferential direction between on the one hand the insulation lining and on the other hand the sleeve and / or the second ring, which limits the risk of relative displacements in particular during temperature variations.

[0022] Indeed, given its radial compression, the elastically deformable organ tends to return to its initial undeformed shape, which allows to increase friction with the insulating lining on one side and with the second bearing ring and / or the bushing on the other. In its mounted position, the radial dimension of said elastically deformable element is strictly less than its radial dimension in the free state, i.e., in the unmounted state.

[0023] By "circumferential direction" is meant the direction which is perpendicular to both the axial direction and to a radius of the bearing device, in other words, tangent to a circle whose center is on the axis of the bearing device.

[0024] By “axial direction”, we mean the direction parallel to the axis of the bearing device.

[0025] By "radial direction" is meant the direction along a radius of the device of bearing, that is to say any direction intersecting the axis of the bearing device and perpendicular to that axis.

[0026] In one embodiment, said elastically deformable member is made at least partly of elastically deformable material. Preferably, said elastically deformable member is made entirely of elastically deformable material. Alternatively, it is possible to make said elastically deformable member partly of elastically deformable material and partly of rigid material.

[0027] Advantageously, said elastically deformable member is made at least partly of electrically insulating material. Preferably, said elastically deformable member is made entirely of electrically insulating material. Alternatively, said elastically deformable member may be made partly of electrically conductive material and partly of electrically insulating material if the electrically conductive material is surrounded by the electrically insulating material in its contact area(s) with the second bearing ring and / or the bushing.

[0028] Said elastically deformable organ is preferably made of a synthetic material or an elastomeric material.

[0029] According to a first conception, said member can be radially in contact with both said surface of the second ring and said surface of the sleeve. In other words, said member is radially interposed between said surface of the second ring and said surface of the sleeve

[0030] According to a second design, said elastically deformable member can be radially in contact with said surface of the second ring and with the insulating lining.

[0031] According to a third design, said elastically deformable member can be radially in contact with the insulation lining and with said surface of the second ring.

[0032] Advantageously, said elastically deformable member is entirely housed between the second ring, the sleeve, and the insulating lining. In other words, said member The elastically deformable part is not accessible from outside the device. Thus, this elastically deformable part is not subjected to shocks.

[0033] In one embodiment, said surface of the second ring is provided with at least one groove extending in the circumferential direction and within which said elastically deformable member is partially housed. Said elastically deformable member may radially bear against the bottom of this groove.

[0034] Alternatively or in combination, said sleeve surface is provided with at least one groove extending in the circumferential direction and within which said elastically deformable member is partially housed. Said elastically deformable member may radially bear against the bottom of this groove.

[0035] If the insulation lining is made of synthetic material or elastomeric material, it makes the device less sensitive to temperature variations.

[0036] In a particular embodiment, the bushing is made of metallic material. The bushing can thus be easily machined to a predetermined radial tolerance.

[0037] According to a first conception, the sleeve delimits the outer surface of said device. In this case, the second ring is the outer ring of the bearing.

[0038] According to a second alternative design, the sleeve defines the inner surface of said device. In this case, the second ring is the inner ring of the bearing.

[0039] In a particular embodiment, the bearing comprises at least one row of rolling elements arranged between raceways of the first and second rings. The rolling elements may be made of metallic material.

[0040] The invention also relates to an electric motor comprising a casing, a shaft and at least one bearing device as defined above and mounted radially between the casing and the shaft. Brief description of the figures

[0041] The present invention will be better understood upon study of the detailed description of embodiments, taken by way of non-limiting examples and illustrated by the accompanying drawings in which:

[0042] [Fig-1] is a half axial cross-sectional view of a bearing device according to an example of the realization of the invention,

[0043] [Fig.2] is a cross-sectional view of a sleeve and an elastic deformable element of the bearing device of the [Fig.1], and

[0044] [Fig.3] is a cross-sectional view of a sleeve and an elastic deformable element according to another example of the realization of the invention. Detailed description of the invention

[0045] The bearing device illustrated in [Fig. 1] comprises a bearing 10 provided with a first ring 12 and a second ring 14 which are able to rotate relative to each other about the axis X-X' of the bearing. In the illustrated embodiment, the first ring 12 is the inner ring of the bearing and the second ring 14 is the outer ring.

[0046] The bearing device is designed so as not to conduct electric currents. The bearing device has integrated electrical insulation.

[0047] The inner ring 12 and outer ring 14 of the bearing are concentric and extend axially along the X-X' axis of the bearing. The inner ring 12 and outer ring 14 are made of steel. The rings are of the solid type.

[0048] In the illustrated embodiment, the bearing 10 also includes a row of rolling elements 16, here balls, interposed radially between the inner ring 12 and the outer ring 14. The rolling elements 16 are made of steel. The bearing 10 also includes a cage 17 for maintaining the regular circumferential spacing of the rolling elements 16. The bearing 10 can further be equipped with seals or sealing flanges.

[0049] The inner ring 12 comprises a cylindrical bore 12a, an axial cylindrical outer surface 12b radially opposed to the bore, and two opposing radial front faces (not referenced) axially delimiting the bore and the outer surface. The bore 12a and the outer surface 12b define the radial thickness of the inner ring 12. The bore 12a forms the inner surface of the inner ring.

[0050] The inner ring 12 further includes an inner raceway 18 for the rolling elements 16 which is formed on the outer surface 12b. The raceway 18 is directed radially outwards.

[0051] The outer ring 14 comprises a cylindrical axial outer surface 14a, a cylindrical bore 14b radially opposed to the outer surface 14a, and two opposing radial front faces 14c, 14d axially delimiting the bore. The outer surface 14a and the bore 14b define the radial thickness of the outer ring 14. The bore 14b forms the inner surface of the outer ring.

[0052] In the illustrated embodiment, the outer surface 14a of the ring has two distinct diameters. Alternatively, the outer surface 14a could have a single diameter.

[0053] The outer ring 14 further includes an outer raceway 20 for the rolling elements 16 which is formed on the bore 14b. The raceway 20 is directed radially inwards.

[0054] In the illustrated embodiment, a groove 22 is formed on the front face 14c of the outer ring. The groove 22 is oriented and axially open towards the outside of the outer ring. The groove 22 has a bottom that is axially offset towards the inside of the ring relative to the front face 14c. The bottom of the groove 22 forms a shoulder. The bottom of the groove 22 extends radially here for manufacturing simplicity. The groove 22 is annular.

[0055] Similarly, a groove 24 is formed on the front face 14d of the outer ring. The groove 24 is oriented and axially open towards the outside of the outer ring. The groove 24 has a bottom that is axially offset towards the inside of the ring relative to the front face 14d. The bottom of the groove 24 forms a shoulder. The bottom of the groove 24 extends radially here. The groove 24 is annular here. The grooves 22, 24 are symmetrical to each other with respect to a median radial plane of the outer ring. The grooves 22, 24 axially delimit the outer surface 14a. Alternatively, the outer ring 14 could be without the grooves 22, 24.

[0056] The bearing device also includes an electrical insulation sleeve 26 mounted on the outer ring 14. The insulation sleeve 26 is mounted on the outer surface 14a of the outer ring 14. The insulation sleeve 26 is integral with the outer ring 14.

[0057] The insulation sleeve 26 includes a sleeve 28 and an insulation packing 30 interposed radially between the outer ring 14 and the sleeve 28. The insulation packing 30 is overmolded on the outer ring 14 and on the sleeve 28.

[0058] As will be described in more detail later, the bearing device also includes an elastically deformable member 32 which is partially embedded inside the insulating lining 30 and here radially interposed between the bushing 28 and the outer ring 14. The elastic member 32 is a separate component from the insulating lining 30.

[0059] The sleeve 28 is annular in shape. The sleeve 28 extends axially. The sleeve 28 is made here in one piece. Alternatively, the sleeve 28 could be made in several pieces supported against each other, for example, two identical pieces. The sleeve 28 comprises an axial cylindrical annular outer surface 28a, and an annular bore 28b radially opposed to the outer surface 28a. The bore 28b forms the inner surface of the sleeve 28. The bore 28b is oriented radially inwards, i.e., towards the side of the outer ring 14.

[0060] The sleeve 28 also includes two opposing radial front faces 28c, 28d axially delimiting the bore and the outer surface. The front faces 28c, 28d define the axial length of the bushing. The outer surface 28a and the bore 28b define the radial thickness of the bushing 28. The outer surface 28a of the bushing defines the outer surface of the bearing device 10. In other words, the outer surface 28a defines the outer diameter of the bearing device 10.

[0061] In the illustrated embodiment, the front faces 28c, 28d of the sleeve are respectively coplanar with the front faces 14c, 14d of the outer ring. Alternatively, other arrangements could be provided. For example, the sleeve 28 could have a smaller or larger axial dimension, remaining axially recessed from the faces 14c, 14d of the outer ring, or projecting from said faces.

[0062] The insulating gasket 30 is made of electrically insulating material. The insulating gasket 30 can, for example, be made of a synthetic material, such as PEEK or PA46, or be made of an elastomeric material, for example rubber.

[0063] The insulating gasket 30 is radially interposed between the outer surface 14a of the outer ring and the bore 28b of the sleeve. The insulating gasket 30 covers the outer surface 14a of the outer ring except in the area of ​​the elastic element 32. The insulating gasket 30 also covers the grooves 22, 24 of the outer ring. The insulating gasket 30 further covers the bore 28b of the sleeve except in the area of ​​the elastic element 32.

[0064] The insulating gasket 30 is here made in two axially spaced parts separated by the elastic element 32. The insulating gasket 30 comprises a discontinuous cylindrical axial outer surface 30a and a discontinuous cylindrical bore 30b radially opposed to the outer surface 30a. The outer surface 30a and the bore 30b are discontinuous in the axial direction due to the axial interposition of the elastic element 32.

[0065] The insulating sleeve 30 also includes two opposing radial front faces 30c, 30d that axially define the bore and the outer surface. The radial front faces 30c, 30d define the axial length of the insulating sleeve 30. The outer surface 30a is in radial contact with the bore 28b of the sleeve. The bore 30b is in radial contact with the outer surface 14a of the outer ring and with the grooves 22, 24. The bore 30b has a stepped shape.

[0066] In the illustrated embodiment, the faces 14c, 30c, 28c and 14d, 30d, 28d of the outer ring, the insulating lining and the sleeve are respectively coplanar.

[0067] Alternatively, other arrangements are possible. For example, the insulating gasket 30 could have a reduced axial dimension and remain axially recessed from the faces 14c, 14d of the outer ring. Alternatively, the The insulating gasket 30 could have an increased axial dimension and extend axially beyond the faces 14c, 14d of the outer ring. In this case, the insulating gasket 30 could at least partially cover these faces 14c, 14d. Alternatively, the insulating gasket 30 could at least partially cover the faces 28c, 28d of the sleeve.

[0068] In another alternative or in combination, the sleeve 28 could extend axially in projection from the insulation lining 30 relative to the faces 30c and 30d, or remain axially recessed from these faces.

[0069] As previously stated, the bearing device comprises the elastic element 32 interposed radially between the sleeve 28 and the outer ring 14. The elastic element 32 is interposed radially between the outer surface 14a of the outer ring and the bore 28b of the sleeve. Thus, the elastic element 32 is in contact with both the outer surface 14a of the outer ring and the bore 28b of the sleeve.

[0070] The parts of the elastic element 32 that are not in contact with the outer surface 14a of the outer ring and the bore 28b of the sleeve are covered by the insulating lining 30. The elastic element 32 is partially covered by the insulating lining 30.

[0071] The elastic element 32 is compressed radially. The elastic element 32 is compressed radially between the outer surface 14a of the outer ring and the bore 28b of the sleeve. In other words, in its mounted position, the radial dimension of the elastic element 32 is strictly less than its radial dimension in the free state.

[0072] The elastic element 32 is made of an elastically deformable material. By way of example, the elastic element 32 may be made of a synthetic material such as SEBS, or of an elastomeric material such as silicone rubber, latex, butyl, EPDM, nitrile, a thermoplastic elastomer, etc. The elastically deformable material of the elastic element 32 is also electrically insulating.

[0073] In the illustrated embodiment, the elastic element 32 has a rectangular profile in cross-section. Alternatively, other polygonal profiles are possible, for example triangular, square or hexagonal, or even a circular, oval, elliptical profile, with lobes, etc.

[0074] In the illustrated embodiment, the elastic element 32 comprises an axial cylindrical outer surface 32a, a cylindrical bore 32b radially opposed to the outer surface 32a, and two opposing radial front faces 32c, 32d axially defining the bore. The outer surface 32a and the bore 32b define the radial dimension of the elastic element 32.

[0075] The outer surface 32a and the bore 32b of the elastic element are respectively radially supported against the bore 28b of the sleeve and against the outer surface 14a of the outer ring. The front faces 32c, 32d are covered by the insulating lining 30.

[0076] To manufacture the bearing device, the following procedure is used.

[0077] In a first step, the bearing 10, the bushing 28 and the elastic element 32 are mounted inside a mold which is intended for overmolding the insulation lining 30. In this position mounted inside the mold, the bushing 28 is radially away from the outer ring 14 of the bearing and the elastic element 32 is radially in contact against the outer ring 14 and against the bushing 28.

[0078] Then, in a second successive step, the insulating seal 30 is overmolded onto both the outer ring 14 of the bearing, the bushing 28, and the faces 32c, 32d of the elastic element. Alternatively, the insulating seal 30 could be overmolded in two phases: a first phase during which the mold bears against the face 32c of the elastic element and the overmolding is carried out on the side of the face 32d, then a second phase with the bearing 10 reversed. The mold then bears against the faces 28d, 30d, 14d of the bushing, the seal, and the outer ring, and the overmolding is carried out against the face 32c of the elastic element.

[0079] Finally, the bearing device, which is in the form of a unit assembly, is extracted from the mold.

[0080] The embodiment illustrated in [Fig. 3], in which the identical elements bear the same reference numerals, differs from the first embodiment in that the bore 28b of the sleeve is provided with a groove 34 that extends circumferentially around the axis X-X' of the sleeve. The groove 34 is annular. The elastic element 32 is partially housed inside the groove 34 and projects radially inwards. The outer surface 32a of the elastic element bears radially against the bottom of the groove 34 of the bore 28b of the sleeve. The front faces 32c, 32d of the elastic element remain axially separated from the flanks of the groove 34. This allows the elastic element to extend radially during its radial compression between the sleeve 28 and the outer ring of the bearing.

[0081] In the illustrated embodiments, the elastic element 32 has an annular shape. Alternatively, the elastic element 32 could be in the form of a ring open at one point on its circumference. Alternatively, the elastic element 32 could have other shapes, for example, a rectangular parallelepiped, and extend over a small angular sector, for example, less than 15°. In this case, it is preferable to provide at least two elastic elements 32 radially between the outer ring 14 and the sleeve 28, preferably diametrically opposed.

[0082] As previously stated, in the illustrated embodiments, the insulation packing 30 is made in two parts spaced axially apart and separated by the elastic element 32. This is due to the annular shape of the elastic element 32. When the elastic element 32 is not annular, the insulation packing 30 is made in one part.

[0083] In the illustrated embodiments, the elastic element 32 is located radially between the outer ring 14 and the sleeve 28, and is also interposed between them.

[0084] Alternatively, before overmolding the insulating seal 30, it might be possible to provide a radial gap between the elastic element 32 and the outer surface 14a of the outer ring, or between the elastic element 32 and the bore 28b of the sleeve. In this case, during the overmolding of the insulating seal 30, a thin layer of material fills this radial gap.

[0085] In this case, the elastic element 32 is interposed radially between the insulating gasket 30 and the bore 28b of the sleeve, or between the insulating gasket 30 and the outer surface 14a of the outer ring. In both cases, the elastic element 32 is again located radially between the outer ring 14 and the sleeve 28.

[0086] In the illustrated embodiments, the elastic element 32 is axially offset with respect to the median radial plane of the device passing through the center of the rolling elements. Alternatively, the elastic element 32 could be centered with respect to this median radial plane, or even be in another offset position with respect to this plane. It is also possible to provide that the elastic element 32 is flush on one side with the front faces of the inner ring 12 and outer ring 14.

[0087] In the illustrated embodiments, the first ring 12 of the bearing is the inner ring and the second ring 14 on which the insulation packing 30 is overmolded is the outer ring.

[0088] Alternatively, an inverted arrangement may be provided in which the second ring 14, onto which the insulating sleeve 30 is overmolded, is the inner ring. In this case, the insulating sleeve is located in the bore 12a of the inner ring. The insulating sleeve is then interposed radially between the bore 12a of the inner ring and the outer surface of the bushing. The insulating sleeve is overmolded at least on the inner surface of the inner ring and at least on the outer surface of the bushing. The elastic element is located radially between the inner ring and the bushing. The bore of the bushing defines the bore of the bearing device.

[0089] In the described embodiments, the device bearing is provided with a single row of rolling elements. Alternatively, the bearing may be provided with several rows of rolling elements. Furthermore, the rolling bearing may include Other types of rolling elements besides balls, for example rollers. In another variant, the bearing can be a sliding bearing without rolling elements.

Claims

Demands

1. A bearing device comprising a bearing (10) having a first ring (12) and a second ring (14) capable of rotating relative to each other, and an insulating sleeve (22) mounted on the second ring (14) of the bearing and having a bushing (28) and an insulating gasket (30) interposed radially between the second ring (14) and the bushing (28) and made of electrically insulating material, the bushing comprising an outer surface (28a) and an inner surface (28b) opposite the outer surface and defining the radial thickness of said bushing, the second ring (14) comprising an outer surface (14a) and an inner surface (14b) opposite the outer surface and defining the radial thickness of said second ring, the insulating gasket (30) being overmolded at least on one of the outer and inner surfaces of the second ring (14) and at least on one of the outer and inside of the socket (28),characterized in that the device further comprises at least one elastically deformable member (32) which is located radially between the second ring (14) and the sleeve (28) and which is partially covered by the insulating lining (30), said elastically deformable member (32) being radially in contact with at least one of said surface of the second ring and of said surface of the sleeve (28) when compressed in the radial direction.

2. Device according to claim 1, wherein said elastically deformable member (32) is made at least partly of elastically deformable material.

3. Device according to claim 1 or 2, wherein said elastically deformable member (32) is made at least partly of electrically insulating material.

4. Device according to any one of the preceding claims, wherein said elastically deformable member (32) is radially in contact with both said surface of the second ring (14) and with said surface of the sleeve (28).

5. Device according to any one of the preceding claims, wherein said elastically deformable member (32) is entirely housed between the second ring (14), the sleeve (28) and the insulating lining (30).

6. Device according to any one of the preceding claims, wherein said elastically deformable member (32) is annular.

7. Device according to any one of the preceding claims, wherein said surface of the second ring (14) or said surface of the sleeve (28) is provided with at least one groove (34) extending in the circumferential direction and within which is housed in part said elastically deformable member (32).

8. Device according to claim 7, wherein said elastically deformable member (32) is radially supported against the bottom of the groove (34).

9. Device according to any one of the preceding claims, wherein said elastically deformable member (32) is made of a synthetic material or of an elastomeric material.

10. Electric motor comprising a housing, a shaft and at least one bearing device according to any one of the preceding claims mounted radially between the housing and the shaft.

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